Air flows from a large reservoir in which the pressure is 450 kPa through a convergent–divergent nozzle. A normal shock wave occurs in the diverging portion of the nozzle at a point where the nozzle area is twice the throat area. Find the Mach numbers on each side of this shock wave. If the Mach number on the exit plane of the nozzle is 0.2, find the back-pressure required to maintain the shock at this location.

In which situation has the independent variable for the experiment been changed? check all that apply. changed from counting the number of duckweed at day 0 and day 14 to counting them every day changed from testing duckweed growth in beakers to testing duckweed growth in large outdoor tanks changed from testing the effect of ph on duckweed growth to testing the effect of light levels on duckweed growth changed from testing the effect of acid ph on duckweed growth to testing the effect of basic ph on duckweed growth